1. Field of the Invention
The present invention relates to a pointing input device in which an operator carries out a pointing input while looking at pointing input information displayed on a display panel. More particularly, the present invention relates to a pointing input device for detecting a pointing input position by means of an optical touch panel, and for carrying out a predetermined command corresponding to the pointing input information when the operator pushes a position where the pointing input information is displayed.
2. Description of the Related Art
A pointing input device is generally known in which an optical touch panel is laminated on a display panel composed of a CRT (cathode-ray tube) or an LCD (liquid crystal display). The display panel displays various kinds of pointing input information, so that an operator points and inputs the position of the desired pointing input information in an input operation area of the optical touch panel by looking at the pointing input information.
The structure of a conventional pointing input device 100 will be hereinafter described with reference to FIGS. 4 and 5. The pointing input device 100 has a case 101, a liquid crystal display panel 102, a transparent glass substrate 103 for protecting a surface of the liquid crystal display panel 102, and an optical touch panel 104 which are each laminated from underneath in the order described above.
A liquid crystal driver (not shown) displays a plurality of kinds of pointing input information 105 on a display area of the liquid crystal display panel 102 in accordance with the application of pointing input. An operator carries out the pointing input as described later, with reference to the pointing input information 105.
The optical touch panel 104 has light-emitting devices 108 arranged along the orthogonal X and Y directions of a rectangular frame 107 at equal intervals, and photoreceptor devices 109 arranged opposite to the light-emitting devices 108 and across the input operation area 107A of the rectangular frame 107. The light-emitting devices 108 sequentially emit light for scanning, and the photoreceptor devices 109 receive the light.
When the operator puts a pen or a finger on any pointing input position inside the input operation area 107A, light beams passing through the pointing input position are intercepted. The photoreceptor devices 109 in the light paths of the light beams do not receive the light with proper timing to the light emission of the corresponding light-emitting devices 108. Thus, it is possible to detect the pointing input to the optical touch panel 104 and X and Y coordinates of the pointing input position.
Since the input operation area 107A enclosed within the rectangular frame 107 is disposed over the display area of the liquid crystal display panel 102, it is possible for the operator to carry out the pointing input, while looking at the pointing input information 105 displayed on the liquid crystal display panel 102 from above through the transparent glass substrate 103.
When the pointing input device 100 detects that the operator retracts the pen or the finger from the pointing input position of the input operation area 107A after detecting the pointing input, the pointing input device 100 outputs push detection data for carrying out a command in accordance with the pointing input position.
On the other hand, several kinds of pointing input information 105 are provided with pointing input areas 106 (shown in broken lines in the drawing) which are located above the pointing input information 105 in the input operation area 107A. The pointing input area 106 corresponds to a predetermined command indicated by the pointing input information 105. When the pen or finger points to the inside of the pointing input area 106, and the push detection data is outputted, the predetermined command corresponding to the pointing input area 106 is carried out.
Accordingly, when the operator points to the display position of the predetermined pointing input information 105, namely points to the inside of the pointing input area 106, and then when the operator retracts the pen or the finger from the pointing input position of the input operation area 107A, the predetermined command corresponding to the pointing input information 105 is carried out.
When the conventional pointing input device 100 detects the pointing input to the input operation area 107A and the position thereof, and also when the operator releases the pointing input by retracting the pen or finger, the push detection data for carrying out the predetermined command is outputted. Therefore, the operator can change the pointing input position and enter the command corresponding to the specific pointing input position, while looking at the pointing input information 105.
The push detection data is outputted every time the pointing input is released, in addition to when the pointing input is carried out by the operator inserting the pen or the finger into the pointing input area 106. Accordingly, there is a problem that the predetermined command can be carried out by mistake, such as when the operator retracts the pen or the finger from the pointing input area 106 for the purpose of simply finishing an operation.
Thus, when releasing the pointing input by retracting the pen or the finger, the operator needs to pay attention to a release position. Also, the operator cannot suspend an operation to think, and the operator cannot rest before completing the operation.
It is possible to attach another push detection switch mechanism for the purpose of outputting the push detection data. In this case, however, there are other problems that the size of the device becomes large, and the operator has to operate with both hands because the push detection switch mechanism cannot be operated with the same finger or the pen for the pointing input.
Furthermore, the pointing input device 100 always detects the pointing input even when the light beam is only momentarily intercepted. Thus, there is a problem that a water droplet, a bug, or the like passing through the input operation area 107A causes the pointing input device 100 to malfunction.